The delivery of a package mailed to a tenant of a multiple tenant building, such as an apartment house or office building, or to a person receiving mail at a centralized pick up point in a rural community, such as may be located for use by tenants of a trailer park, has been a time consuming procedure both for the mailman charged with its delivery and for the intended recipient. In this respect, letter boxes normally provided for tenants of a multiple tenant building or trailer park are not of a size sufficient to receive medium to large size packages, and thus it has been necessary for the mailman to carry such packages directly to the door of the intended recipient. In the absence of the recipient, it is necessary for the mailman to return the package to the Post Office to await its personal pickup by the recipient.
A solution to the foregoing problem is offered by a mailbox unit of the type described in U.S. Pat. No. 3,790,244. In this patented unit, a plurality of large sized package storage cabinets are provided in proximity to a plurality of conventionally sized, key controlled letter boxes permanently assigned one to each tenant. The door of each storage cabinet is provided with a pair of key operated locks, namely, a custodian lock, which is operable by a key continuously retained in the possession of the mailman, and an access or recipient lock, which is overcontrolled by the custodian lock for single-shot door opening operation by an access key placed in the temporary custody of an intended recipient of a package.
More specifically, when the mailman wishes to deliver a package, he places the package in one of the storage cabinets and then places its associated access key, which is appropriately numbered or otherwise marked in conformity with such cabinet, in the intended recipient's letter box. The presence of an access key in his letter box automatically advises the intended recipient that he has received a package and he then uses such key to open the door of the appropriate storage cabinet to gain access to his package. As the access key is turned to unlock the access lock in order to permit opening of the storage cabinet door, a latch device controlled by the custodian lock automatically locks the access lock in unlocked condition, with the result that its access key is "captured" or retained in the access lock. During a subsequent mail delivery, the mailman may reuse the now empty storage cabinet by placing another package therein and then employing his key to momentarily unlock the custodian lock in order to release the access lock for return to its cabinet door locked condition. The access key may then be removed and deposited in an appropriate letter box.
A drawback of the patented unit is that the door of a storage cabinet is permitted to remain in an unlocked condition for an undetermined period of time between operation of the access lock for package removal purposes and a subsequent mail delivery, when the mailman may again lock the cabinet door in closed condition. Allowing an unattended cabinet to remain in an unlocked condition is undesirable in that it exposes the door and inside of the cabinet to vandalism, and permits persons to deposit trash and other undersirable objects within the cabinet. A further drawback of the patented unit is that it requires fitting each storage cabinet with a separate key controlled custodian lock, which is required to be sequentially operated with the access lock each time the latter is returned to locked condition.